U.S. patent number 6,695,158 [Application Number 10/068,563] was granted by the patent office on 2004-02-24 for crane with self-raising mast.
This patent grant is currently assigned to Manitowoc Crane Companies, Inc.. Invention is credited to John Taylor, Arthur Zuehlke.
United States Patent |
6,695,158 |
Taylor , et al. |
February 24, 2004 |
**Please see images for:
( Certificate of Correction ) ** |
Crane with self-raising mast
Abstract
An apparatus and method of self-raising a mast for a crane
having an upper works rotatably mounted on a lower works and a boom
pivotally mounted on the upper works, the boom being supported by
boom hoist rigging and a mast pivotally connected to the upper
works. The crane further includes a self-raising mast assembly for
controlling the position of the mast when the mast is not connected
to the boom and is not supportable by the boom hoist rigging. The
self-raising mast assembly comprises a mast raising yoke pivotally
connected to the upper works, a hydraulic mast raise cylinder
pivotally connected between the upper works and the mast raising
yoke, and a hydraulic system for controlling the mast raise
cylinder.
Inventors: |
Taylor; John (Manitowoc,
WI), Zuehlke; Arthur (Manitowoc, WI) |
Assignee: |
Manitowoc Crane Companies, Inc.
(Reno, NV)
|
Family
ID: |
22083338 |
Appl.
No.: |
10/068,563 |
Filed: |
February 4, 2002 |
Current U.S.
Class: |
212/298; 212/270;
212/299 |
Current CPC
Class: |
B66C
23/82 (20130101) |
Current International
Class: |
B66C
23/82 (20060101); B66C 23/00 (20060101); B66C
023/34 () |
Field of
Search: |
;212/298,299,270 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Brahan; Thomas J.
Attorney, Agent or Firm: Brinks Hofer Gilson & Lione
Claims
What is claimed is:
1. A crane having an upper works rotatably mounted on a lower works
and a boom pivotally mounted on the upper works, said boom being
supported by boom hoist rigging and a mast pivotally connected to
the upper works, said crane further having a self-raising mast
assembly for controlling the position of the mast when said mast is
not connected to the boom, said self-raising mast assembly
comprising: a) a mast raising yoke pivotally connected to the upper
works and having an axis of rotation that is coincident with the
pivotal connection of the mast to the upper works, said mast
raising yoke being configured to engage and support said mast when
said mast is not supportable by said boom hoist rigging, and
disengaged from said mast when said mast is supportable by said
boom hoist rigging; b) a hydraulic mast raise cylinder pivotally
connected between the upper works and said mast raising yoke, said
hydraulic mast raise cylinder being extendable and retractable so
as to rotate said mast raising yoke about said axis of rotation;
and c) a hydraulic system for controlling the extension and
retraction of said hydraulic mast raise cylinder.
2. The crane according to claim 1 wherein said mast raising yoke
comprises a rearward arm and a forward arm, said rearward arm being
configured to engage and support said mast when said mast is
between an approximately horizontal stored position towards a
rearward portion of the upper works and an approximately vertical
position, said forward arm being configured to engage and support
said mast when said mast is near a horizontal position towards a
forward portion of the crane.
3. The crane according to claim 2 wherein said rearward arm and
said forward arm each comprise an engagement member configured to
engage a lifting member on the mast, the engagement member on the
rearward arm being engaged by said lifting member when said mast is
between the stored position and the approximately vertical
position, the engagement member on the forward arm being engaged by
the lifting member when said mast is near the horizontal position
towards the forward portion of the crane.
4. The crane according to claim 2 wherein said self-raising mast
assembly comprises a pair of self-raising mast assemblies, each
self-raising mast assembly being positioned to engage a leg of said
mast.
5. The crane according to claim 2 wherein said mast is pivotal
through an angle of approximately 180.degree..
6. The crane according to claim 2 wherein said mast raising yoke
further comprises a lever arm pivotally connected to said mast
raise cylinder.
7. The crane according to claim 1 further comprising a
microprocessor-based controller for coordinating the extension and
contraction of the hydraulic mast raise cylinder with extension and
contraction of the boom hoist rigging.
8. The crane according to claim 7 wherein the microprocessor-based
controller maintains a proper balance of forces in the boom hoist
rigging and on the mast.
9. A crane having an upper works rotatably mounted on a lower works
and a boom pivotally mounted on the upper works, said boom being
supported by boom hoist rigging and a moving mast pivotally
connected to the upper works, said boom hoist rigging being
connected between a rearward portion of said upper works and an
upper end of said mast, and boom pendants being connected between
the upper end of said mast and said boom, wherein said crane
further comprises self-raising mast assembly for raising and
lowering the mast when said mast is not connected to the boom and
is not supportable by the boom hoist rigging, said self-raising
mast assembly comprising: a) a mast raising yoke pivotally
connected to the upper works and having an axis of rotation that is
coincident with the pivotal connection of the mast to the upper
works, said mast raising yoke having a rearward arm configured to
engage and support said mast when said mast is between an
approximately horizontal stored position towards the rearward
portion of the upper works and an approximately vertical position,
said rearward arm being disengaged from said mast when said mast is
supported by said boom hoist rigging; b) a hydraulic mast raise
cylinder pivotally connected between the upper works and said mast
raising yoke, said hydraulic mast raise cylinder being extendable
and retractable so as to rotate said mast raising yoke about said
axis of rotation; and c) a hydraulic system for controlling the
extension and retraction of said hydraulic mast raise cylinder.
10. The crane according to claim 9 wherein said mast raising yoke
further comprises a forward arm, said forward arm being configured
to engage and support said mast when said mast is near a horizontal
position towards a forward portion of the crane, said forward arm
being disengaged from said mast when said mast is supported by said
boom hoist rigging.
11. The crane according to claim 10 wherein said rearward arm and
said forward arm each comprise an engagement slot configured to
engage a lifting pin on the mast, the engagement slot on the
rearward arm being engaged by said lifting pin when said mast is
between the stored position and the approximately vertical
position, the engagement slot on the forward arm being engaged by
the lifting pin when said mast is near the horizontal position
towards a forward portion of the crane.
12. The crane according to claim 11 wherein said self-raising mast
assembly comprises a pair of self-raising mast assemblies, each
self-raising mast assembly being positioned to engage a leg of said
mast.
13. The crane according to claim 11 wherein said mast raising yoke
further comprises a lever arm pivotally connected to said mast
raise cylinder.
14. The crane according to claim 11 wherein said mast raising yoke
is pivotal between a stored position and a mast backstop position,
said rearward arm being generally horizontal when the mast raising
yoke is in the stored position and generally vertical when the mast
raising yoke is in the backstop position, said mast raising yoke
being pivotal between the stored position and the mast backstop
position by extension and contraction of the hydraulic mast raise
cylinder.
15. The crane according to claim 14 wherein, when said mast raising
yoke is in the mast backstop position, the rearward arm prevents
said mast from falling onto the rearward portion of the upper
works.
16. The crane according to claim 14 wherein, when said mast raising
mast raising yoke is in the stored position, the forward arm
prevents said mast from falling when said mast is near the
horizontal position towards the forward portion of the crane.
17. The crane according to claim 11 wherein said mast is pivotal
through an angle of approximately 180.degree. when not connected to
the boom.
18. The crane according to claim 17 wherein the mast, when not
connected to the boom, is supportable by the rearward arm of the
mast raising yoke when the angle of the mast is between
approximately 0.degree. and 115.degree. as measured from the stored
position, is supportable by the boom hoist rigging when the angle
of the mast is between approximately 115.degree. and 160.degree.,
and is supportable by the forward arm of the mast raising yoke when
the angle of the mast is between approximately 160.degree. and
180.degree..
19. The crane according to claim 11 wherein the engagement slot on
said rearward arm and the engagement slot on said forward arm are
separated by an angle of approximately 160.degree., said angle
being measured about the axis of rotation of said mast raising
yoke.
20. The crane according to claim 9 further comprising a
microprocessor-based controller for coordinating the extension and
contraction of the hydraulic mast raise cylinder with extension and
contraction of the boom hoist rigging.
21. The crane according to claim 20 wherein the
microprocessor-based controller maintains a proper balance of
forces in the boom hoist rigging and on said mast when said mast is
not connected to the boom.
22. A crane having an upper works rotatably mounted on a lower
works and a boom pivotally mounted on the upper works, said boom
being supported by boom hoist rigging and a moving mast pivotally
connected to the upper works, said boom hoist rigging being
connected between a rearward portion of said upper works and an
upper end of said mast, and boom pendants being connected between
the upper end of said mast and said boom, wherein said crane
further comprises self-raising mast assembly for raising and
lowering the mast when said mast is not connected to the boom and
is not supportable by the boom hoist rigging, said self-raising
mast assembly comprising: a) a mast raising yoke pivotally
connected to the upper works and having an axis of rotation that is
coincident with the pivotal connection of the mast to the upper
works, said mast raising yoke having a rearward arm and a forward
arm, said rearward arm being configured to engage and support said
mast when said mast is between an approximately horizontal stored
position toward the rearward portion of the upper works and an
approximately vertical position, said forward arm being configured
to engage and support said mast when said mast is near a horizontal
position towards a forward portion of the crane, said rearward arm
and said forward arm being disengageable from said mast when said
mast is supported by said boom hoist rigging; b) a hydraulic mast
raise cylinder pivotally connected between the upper works and said
mast raising yoke, said hydraulic mast raise cylinder being
extendable and retractable so as to rotate said mast raising yoke,
the mast being raised or lowered by the rotation of said mast
raising yoke when said mast is engaged by said rearward arm or said
forward arm; c) a hydraulic system for controlling the extension
and retraction of said hydraulic mast raise cylinder; and d) a
microprocessor-based controller for controlling said hydraulic
system, the control of said hydraulic system being coordinated with
extension or contraction of the boom hoist rigging.
23. The crane according to claim 22 wherein said rearward arm and
said forward arm each comprise an engagement slot configured to
engage a lifting pin on the mast, the engagement slot on the
rearward arm being engaged by said lifting pin when said mast is
between the stored position and the approximately vertical
position, the engagement slot on the forward arm being engaged by
the lifting pin when said mast is near the horizontal position
towards the forward portion of the crane.
24. The crane according to claim 22 wherein said mast raising yoke
further comprises a lever arm pivotally connected to said mast
raise cylinder.
25. The crane according to claim 22 wherein said mast raising yoke
is pivotal between a stored position and a mast backstop position,
said rearward arm being generally horizontal when the mast raising
yoke is in the stored position and generally vertical when the mast
raising yoke is in the backstop position, said mast raising yoke
being pivotal between the stored position and the mast backstop
position by extension and contraction of the hydraulic mast raise
cylinder.
26. The crane according to claim 25 wherein, when said mast raising
yoke is in the mast backstop position, the rearward arm prevents
said mast from falling on to the rearward portion of the upper
works, and further wherein, when said mast raising mast raising
yoke is in the stored position, the forward arm prevents said mast
from falling when said mast is near the horizontal position towards
the forward portion of the crane.
27. The crane according to claim 22 wherein the
microprocessor-based controller is connected to a load-pin on said
mast raise cylinder, said load pin providing an electrical signal
to said microprocessor-based controller that is proportional to a
load applied to the mast raise cylinder by said mast when said mast
is engaged by said rearward arm or said forward arm.
28. The crane according to claim 22 wherein the hydraulic system
comprises a closed loop hydraulic system, said closed loop
hydraulic system being hydraulically connected to a load hoist pump
through a control valve, said control valve regulating a hydraulic
pressure in the closed loop hydraulic system in response to
electrical signals received from the microprocessor-based
controller.
29. A method of self-raising a mast for a crane having an upper
works rotatably mounted on a lower works and a boom pivotally
mounted on the upper works, said boom being supported by boom hoist
rigging and a mast pivotally connected to the upper works, said
crane further having a self-raising mast assembly for controlling
the position of the mast when said mast is not connected to the
boom and is not supportable by the boom hoist rigging, said
self-raising mast assembly comprising a mast raising yoke pivotally
connected to the upper works and having an axis of rotation, a
hydraulic mast raise cylinder pivotally connected between the upper
works and the mast raising yoke, and a hydraulic system for
controlling the mast raise cylinder, said method comprising the
sequential steps of: a) engaging the mast with the mast raising
yoke when the mast is in a rearwardly extending stored position on
a rearward portion of the upper works; b) extending the mast raise
cylinder to rotate the mast raising yoke in a first direction so as
to pivot the mast upwardly from the stored position to a forwardly
leaning position; c) supporting the mast with the boom hoist
rigging when the mast is in the forwardly leaning position; d)
retracting the mast raise cylinder to rotate the mast raising yoke
in a second direction so as to disengage said mast raising yoke
from said mast when the mast is supported by the boom hoist
rigging; e) extending the boom hoist rigging to lower the mast
towards a forwardly extending fully forward position; f) engaging
the mast with the mast raising yoke when the mast is near the fully
forward position; g) extending the mast raise cylinder to rotate
the mast raising yoke in the first direction so as to pivot the
mast downwardly to the fully forward position; and h) connecting
the mast to the boom.
30. The method according to claim 29 wherein, when the mast is not
connected to the boom, the mast is used to lift and assemble crane
components to the crane.
31. A method of self-raising a mast for a crane having an upper
works rotatably mounted on a lower works and a boom pivotally
mounted on the upper works, said boom being supported by boom hoist
rigging and a mast pivotally connected to the upper works, said
crane further having a self-raising mast assembly for controlling
the position of the mast when said mast is not connected to the
boom and is not supportable by the boom hoist rigging, said
self-raising mast assembly comprising a mast raising yoke having a
rear ward arm and a forward arm pivotally connected to the upper
works and having an axis of rotation that is aligned with an axis
of rotation of said mast, a hydraulic mast raise cylinder pivotally
connected between the upper works and the mast raising yoke, and a
hydraulic system for controlling the mast raise cylinder, said
method comprising the sequential steps of: a) engaging the mast
with the rearward arm of the mast raising yoke when the mast is in
a rearwardly extending stored position on a rearward portion of the
upper works, said rearward arm having an engagement slot that
engages a lifting pin on the mast; b) extending the mast raise
cylinder to rotate the mast raising yoke in a first direction so as
to pivot the mast upwardly from the stored position to a forwardly
leaning position; c) retracting the mast raise cylinder to rotate
the mast raising yoke in a second direction so as to disengage the
rearward arm of the mast raising yoke from said mast while the mast
is in the forwardly leaning position; d) supporting the mast with
the boom hoist rigging while the mast is in the forwardly leaning
position; e) extending the boom hoist rigging to lower the mast
towards a fully forward position; f) engaging the mast with the
forward arm of the mast raising yoke when the mast is near the
fully forward position, said forward arm having an engagement slot
that engages the lifting pin on the mast; g) extending the mast
raise cylinder to rotate the mast raising yoke in the first
direction so as to pivot the mast downwardly to the fully forward
position in front of the upper works; h) connecting the mast to the
boom; i) retracting the mast raise cylinder to rotate the mast
raising yoke in the second direction so as to pivot the mast
upwardly from the fully forward position in front of the upper
works; and j) retracting the boom hoist rigging to raise the mast
and lift the boom into a crane operational range.
32. The method according to claim 31 wherein, when the mast is not
connected to the boom, the mast is used to lift and assemble crane
components to the crane.
33. A crane having an upper works rotatably mounted on a lower
works and a boom pivotally mounted on the upper works, said boom
being supported by boom hoist rigging and a mast pivotally
connected to the upper works, said crane further having a
self-raising mast assembly for controlling the position of the mast
when said mast is not connected to the boom, said self-raising mast
assembly comprising: a) a mast raising yoke pivotally connected to
the upper works and having an axis of rotation, said mast raising
yoke being configured to engage and support said mast when said
mast is not supportable by said boom hoist rigging, and disengaged
from said mast when said mast is supportable by said boom hoist
rigging; b) a hydraulic mast raise cylinder pivotally connected
between the upper works and said mast raising yoke, said hydraulic
mast raise cylinder being extendable and retractable so as to
rotate said mast raising yoke about said axis of rotation; and c) a
hydraulic system for controlling the extension and retraction of
said hydraulic mast raise cylinder, wherein said mast raising yoke
comprises a rearward arm and a forward arm, said rearward arm being
configured to engage and support said mast when said mast is
between an approximately horizontal stored position towards a
rearward portion of the upper works and an approximately vertical
position, said forward arm being configured to engage and support
said mast when said mast is near a horizontal position towards a
forward portion of the crane.
34. The crane according to claim 33 wherein said rearward arm and
said forward arm each comprise an engagement member configured to
engage a lifting member on the mast, the engagement member on the
rearward arm being engaged by said lifting member when said mast is
between the stored position and the approximately vertical
position, the engagement member on the forward arm being engaged by
the lifting member when said mast is near the horizontal position
towards the forward portion of the crane.
35. The crane according to claim 33 wherein said self-raising mast
assembly comprises a pair of self-raising mast assemblies, each
self-raising mast assembly being positioned to engage a leg of said
mast.
36. The crane according to claim 33 wherein said mast is pivotal
through an angle of approximately 180.degree..
37. The crane according to claim 33 wherein said mast raising yoke
further comprises a lever arm pivotally connected to said mast
raise cylinder.
38. The crane according to claim 33 further comprising a
microprocessor-based controller for coordinating the extension and
contraction of the hydraulic mast raise cylinder with extension and
contraction of the boom hoist rigging.
39. The crane according to claim 38 wherein the
microprocessor-based controller maintains a proper balance of
forces in the boom hoist rigging and on the mast.
40. A crane having an upper works rotatably mounted on a lower
works and a boom pivotally mounted on the upper works, said boom
being supported by boom hoist rigging and a moving mast pivotally
connected to the upper works, said boom hoist rigging being
connected between a rearward portion of said upper works and an
upper end of said mast, and boom pendants being connected between
the upper end of said mast and said boom, wherein said crane
further comprises self-raising mast assembly for raising and
lowering the mast when said mast is not connected to the boom and
is not supportable by the boom hoist rigging, said self-raising
mast assembly comprising: a) a mast raising yoke pivotally
connected to the upper works and having an axis of rotation, said
mast raising yoke having a rearward arm configured to engage and
support said mast when said mast is between an approximately
horizontal stored position towards the rearward portion of the
upper works and an approximately vertical position, said rearward
arm being disengaged from said mast when said mast is supported by
said boom hoist rigging; b) a hydraulic mast raise cylinder
pivotally connected between the upper works and said mast raising
yoke, said hydraulic mast raise cylinder being extendable and
retractable so as to rotate said mast raising yoke about said axis
of rotation; and c) a hydraulic system for controlling the
extension and retraction of said hydraulic mast raise cylinder,
wherein said mast raising yoke further comprises a forward arm,
said forward arm being configured to engage and support said mast
when said mast is near a horizontal position towards a forward
portion of the crane, said forward arm being disengaged from said
mast when said mast is supported by said boom hoist rigging.
41. The crane according to claim 40 wherein said rearward arm and
said forward arm each comprise an engagement slot configured to
engage a lifting pin on the mast, the engagement slot on the
rearward arm being engaged by said lifting pin when said mast is
between the stored position and the approximately vertical
position, the engagement slot on the forward arm being engaged by
the lifting pin when said mast is near the horizontal position
towards a forward portion of the crane.
42. The crane according to claim 41 wherein said self-raising mast
assembly comprises a pair of self-raising mast assemblies, each
self-raising mast assembly being positioned to engage a leg of said
mast.
43. The crane according to claim 41 wherein said mast raising yoke
further comprises a lever arm pivotally connected to said mast
raise cylinder.
44. The crane according to claim 41 wherein said mast raising yoke
is pivotal between a stored position and a mast backstop position,
said rearward arm being generally horizontal when the mast raising
yoke is in the stored position and generally vertical when the mast
raising yoke is in the backstop position, said mast raising yoke
being pivotal between the stored position and the mast backstop
position by extension and contraction of the hydraulic mast raise
cylinder.
45. The crane according to claim 44 wherein, when said mast raising
yoke is in the mast backstop position, the rearward arm prevents
said mast from falling onto the rearward portion of the upper
works.
46. The crane according to claim 44 wherein, when said mast raising
mast raising yoke is in the stored position, the forward arm
prevents said mast from falling when said mast is near the
horizontal position towards the forward portion of the crane.
47. The crane according to claim 41 wherein said mast is pivotal
through an angle of approximately 180.degree. when not connected to
the boom.
48. The crane according to claim 47 wherein the mast, when not
connected to the boom, is supportable by the rearward arm of the
mast raising yoke when the angle of the mast is between
approximately 0.degree. and 115.degree. as measured from the stored
position, is supportable by the boom hoist rigging when the angle
of the mast is between approximately 115.degree. and 160.degree.,
and is supportable by the forward arm of the mast raising yoke when
the angle of the mast is between approximately 160.degree. and
180.degree..
49. The crane according to claim 41 wherein the engagement slot on
said rearward arm and the engagement slot on said forward arm are
separated by an angle of approximately 160.degree., said angle
being measured about the axis of rotation of said mast raising
yoke.
50. The crane according to claim 40 further comprising a
microprocessor-based controller for coordinating the extension and
contraction of the hydraulic mast raise cylinder with extension and
contraction of the boom hoist rigging.
51. The crane according to claim 40 wherein the
microprocessor-based controller maintains a proper balance of
forces in the boom hoist rigging and on said mast when said mast is
not connected to the boom.
Description
BACKGROUND OF THE INVENTION
The present application relates to construction equipment, such as
cranes. In particular, the present application relates to a crane
having several unique and inventive aspects, such as a self-raising
mast, a hydraulic circuit for raising the mast, and a
microprocessor-based controller for controlling the mast raising
procedure. The present application also relates to a method of
self-raising the mast and assembling the crane.
Construction equipment, such as cranes or excavators, must often be
moved from one job site to another. Moving a crane or an excavator
can be a formidable task when the machine is large and heavy. For
example, highway limits on vehicle-axle loads must be observed, and
overhead obstacles can dictate long, inconvenient routings to the
job site.
One solution to improving the mobility of large construction
machines, such as cranes, is to disassemble them into smaller, more
easily handled components. The separate components can then be
transported to the new job site where they are reassembled.
The typical practice has been to use an assist crane to disassemble
the crane into the separate components. The assist crane is then
used to load the components onto their respective transport
trailers. Once at the new job site, another assist crane is used to
unload the components and reassemble the crane. As the components
for a large crane can weigh as much as 80,000 lbs., the capacity of
the assist crane required represents a very significant transport
expense.
As a result, designers have attempted to develop self-handling
systems for assembling and disassembling cranes. The majority of
the self-handling systems developed thus far have been directed to
smaller cranes that only need to be disassembled into a few
components.
The development of self-handling systems for larger cranes,
however, has met with limited success. One reason for this is that
larger cranes need to be disassembled into numerous components,
thus requiring time-consuming disassembly and reassembly
procedures. For example, a large capacity crane typically uses a
complicated and cumbersome rigging system to control the angle of
the boom. Boom rigging system components such as the equalizer, the
mast, and wire rope rigging are heavy and difficult to disassemble
for transport. Another reason for the limited success of prior art
self-assembling cranes is that they typically rely on additional
crane components that are used only for assembling and
disassembling the crane. For example, some self-assembling cranes
require additional wire rope guides and sheaves on the boom butt so
that a load hoist line can be used with the boom butt to lift
various crane components during the assembly process.
An example of a prior art method for assembling and disassembling a
typical large capacity crawler crane is disclosed in U.S. Pat. No.
5,484,069, titled "Process For Self-Disassembling A Crawler Crane"
("the '069 patent"). In particular, this patent is directed to a
type of crawler crane having a mast that is supported by a
backhitch.
Another example of a prior art method for assembling and
disassembling a different type of crawler crane is disclosed in
U.S. Pat. No. 6,062,405, titled "Hydraulic Boom Hoist Cylinder
Crane" ("the '405 patent"). This patent is directed to a type of
crane that utilizes hydraulic cylinders to control the angle of the
boom.
The '069 patent and the '405 patent are both examples of
self-assembling cranes that require the use of the boom butt to
lift and position components for assembly on to the crane. As a
consequence, additional sheaves must be included on the boom butt
for the self-assembling procedure. It is therefore desirable to
provide a crane and method of self-assembly which eliminates, or at
least reduces, the use of the boom butt during the self-assembling
procedure.
In addition to the above, some types of cranes utilize a moving or
live mast. A crane having a moving or live mast is connected
directly to the boom by one or more boom pendants. The boom angle
is controlled by boom hoist rigging, which is connected between the
mast and the upper works of the crane. The mast and the boom move
together as the boom angle is changed. The mast must typically be
disconnected from the boom and stored horizontally on top of the
crane for transport between job sites. Moreover, the masts on these
types of cranes are often very long and heavy, and are consequently
difficult to handle during the assembly process. It is therefore
desirable to provide a crane having a self-raising mast. It is also
desirable to provide a system and method of controlling the mast
self-raising procedure that is safe, efficient and easy to
implement.
BRIEF SUMMARY OF THE INVENTION
In preferred aspects, the present invention comprises a crane
having an upper works rotatably mounted on a lower works, a boom
pivotally mounted on the upper works, a mast pivotally mounted on
the upper works and pendantly connected to the boom, and boom hoist
rigging connected to the mast for controlling the angle of the
boom. The invention further comprises a self-raising mast assembly
for controlling the position of the mast when the mast is not
connected to the boom. The self-raising mast assembly comprises a
mast raising yoke, a hydraulic mast raise cylinder, and a hydraulic
system.
The mast raising yoke is pivotally connected to the upper works and
preferably has an axis of rotation that is aligned with the axis of
rotation of the mast. The mast raising yoke is configured to engage
and support the mast when the mast is not within the mast operating
range, and is disengaged from the mast when the mast is within the
mast operating range, the mast being supportable by the boom hoist
rigging when the mast is within the mast operating range.
The hydraulic mast raise cylinder is pivotally connected between
the upper works and the mast raising yoke. The hydraulic mast raise
cylinder is extendable and retractable so as to rotate the mast
raising yoke. The hydraulic system controls the extension and
retraction of the hydraulic mast raise cylinder.
The preferred method of self-raising the mast comprises the steps
of first engaging the mast with the mast raising yoke when the mast
is in a rearwardly extending stored position on a rearward portion
of the upper works, then extending the mast raise cylinder to
rotate the mast raising yoke in a first direction so as to pivot
the mast upwardly from the stored position to a forwardly leaning
position. When the mast is in the forwardly leaning position, the
mast is then supported with the boom hoist rigging, while the mast
raise cylinder is retracted to rotate the mast raising yoke in a
second direction so as to disengage said mast raising yoke from the
mast. The boom hoist rigging is then extended to lower the mast
towards a forwardly extending fully forward position in front of
the upper works, where it is then engaged by the mast raising yoke.
The mast raise cylinder is then extended to rotate the mast raising
yoke in the first direction so as to pivot the mast downwardly to
the fully forward position. The mast can then be connected to the
boom.
The self-raising mast assembly and method permits the mast to be
raised and lowered during the assembly process without the need for
a separate crane, and overcomes many of the problems identified
above. In particular, the self-raising mast assembly and method
permits the mast to be raised from and lowered to a stored position
on the rearward portion of the upper works. The assembly and method
also permits the mast to be raised from and lowered to a fully
forward position in front of the upper works. Moreover, the
assembly and method permits the mast to be used for lifting and
assembling crane components during the crane self-assembly and
self-disassembly process.
These and other advantages, as well as the invention itself, will
become apparent in the details of construction and operation as
more fully described and claimed below. Moreover, it should be
appreciated that several aspects of the invention can be used with
other types of cranes, machines or equipment.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 is a right side elevational view of a complete crane
incorporating a self-raising mast made in accordance with the
teachings of this invention.
FIG. 2 is a left side elevational view of the partially assembled
crane with the mast in the stored position.
FIG. 3 is a partial sectional view of the crane taken along line
3--3 of FIG. 2 showing the location of the self-raising mast
assemblies.
FIG. 4 is an enlarged view of detail A of FIG. 3 showing the
principal components of a self-raising mast assembly.
FIG. 5 is a partial sectional view of the crane taken along line
5--5 of FIG. 3 showing the location of the self-raising mast
assemblies.
FIG. 6 is an enlarged view of detail B of FIG. 5 showing the
principal components of a self-raising mast assembly.
FIGS. 7-10 are right side elevational views of the crane in
sequential stages of the self-raising mast procedure.
FIGS. 11-14 are schematic views of the self-raising mast assembly
in sequential stages of the self-raising mast procedure.
FIGS. 15-16 are right side elevational views of the crane in
sequential stages of the boom assembly.
FIG. 17 is an isometric view of the crane upper works showing the
mast being raised during the self-raising mast procedure.
FIG. 18 is a schematic of the hydraulic circuit that controls the
self-raising mast assemblies.
DETAILED DESCRIPTION OF THE INVENTION
While the present invention will find application in all types of
cranes or construction machines, the preferred embodiment of the
invention is described in conjunction with the crawler crane 10 of
FIG. 1. The crawler crane 10 includes an upper works 12 having a
rotating bed 14 that is rotatably connected to a lower works 16 by
a swing bearing 18. The lower works 16 includes a car body 20,
counterweights 22, and two independently powered crawlers 24.
The upper works 12 includes a boom 26 pivotally connected to the
upper works 12. The boom 26 comprises a boom top 28 and a tapered
boom butt 30. The boom 26 may also include one or more boom inserts
32 connected between the boom top 28 and the boom butt 30 to
increase the overall length of the boom 26. A mast 34 is pivotally
connected to the upper works 12. The boom 26 is connected to the
mast 34 by one or more boom pendants 36.
The angle of the boom 26 is controlled by boom hoist rigging 38
connected between the upper works 12 and the mast 34. As best seen
in FIG. 17, the boom hoist rigging 38 comprises a boom hoist rope
40 that passes (reeved) around a sheave assembly 42 on the upper
end of the mast 34 and a sheave assembly 44 on the rear end of the
upper works 12. One end of the boom hoist rope 40 is typically
anchored to the upper works 12, while the other end is anchored to
and wrapped around the boom hoist drum 46.
The mast 34 supports the connection between the boom hoist rigging
38 and the boom pendants 36 at a location that is distanced from
the axis of the boom 26 to optimize the forces in the boom pendants
36 and the boom hoist rigging 38. This arrangement also permits the
boom hoist rigging 38 to impart a force having a component that is
perpendicular to the axis of the boom 26. This force is transferred
to the end of the boom 26 by the boom pendants 36. Because the
weight of the boom 26 is significantly greater than the weight of
the mast 34 and the boom hoist rigging 38, the boom hoist rope 40
and the boom pendants 36 are always in tension as long as the boom
26 is within the normal operating range of the crane 10.
Conversely, the mast 34 is always in compression as long as the
boom 26 is within the normal operating range of the crane 10. A
boom backstop 48 is provided to prevent the boom 26 from exceeding
a safe operating angle (see FIG. 1).
Rotation of the boom hoist drum 46 in one direction (e.g.,
clockwise) will retract the boom hoist rope 40, thereby shortening
the length of the boom hoist rigging 38 and causing the upper end
of the mast 34 to be pulled towards the rear of the upper works 12.
This in turn raises the end of the boom 26 (i.e., increases the
boom angle). Likewise, rotation of the boom hoist drum 46 in the
opposite direction (e.g., counter-clockwise) will pay out the boom
hoist rope 40, thereby increasing the length of the boom hoist
rigging 38 and allowing the upper end of the mast 34 to be pulled
away from rear of the upper works 12 by the weight of the boom 26.
This action results in the lowering of the end of the boom 26
(i.e., decreases the boom angle).
The upper works 12 further includes one or more load hoist lines 50
for lifting loads. Each load hoist line 50 is passed (reeved)
around a load hoist line drum 52 supported on the rotating bed 14
of the upper works 12. The load hoist line drums 52 are rotated to
either pay out or retrieve the load hoist lines 50. The load hoist
lines 50 are reeved around a plurality of boom top sheaves 54
located at the upper end of the boom top 28. The boom may also
include one or more wire rope guides 56 attached to upper surface
of the boom 26 to prevent the load hoist lines 50 from interfering
with the lattice structure of the boom 26. A hook block (not shown)
is typically attached to each load hoist line 50.
As best seen in FIG. 17, the upper works 12 further includes a
power plant 58, such as a diesel engine, and a counterweight
assembly 22 (see FIG. 1). The power plant 58 supplies power for the
various mechanical and hydraulic operations of the crane 10,
including movement of the crawlers 24, rotation of the rotating bed
14, rotation of the load hoist line drums 52, and rotation of the
boom hoist drum 46. Operation of the various functions of the crane
10 is controlled from the operator's cab 60.
In the preferred embodiment shown, the mast 34 is comprised of a
steel frame having spaced apart rectangular legs 62. The mast 34
should not interfere with the operation of the load hoist lines 50
or the boom backstop 48. In addition, the mast 34 should be
configured so as to permit the mast 34 to be lowered to an
approximately horizontal stored position on top of the upper works
12 when the crane 10 has been disassembled for transport, as shown
in FIG. 2. This permits the overall height of the disassembled
crane 10 to be minimized so that highway height restrictions will
not be violated during transport to and from the job site. As will
be explained below, the mast 34 is ordinarily not disassembled from
the crane 10 during transport. The mast 34 should also be
configured so as to permit the mast 34 to be lowered to an
approximately horizontal fully forward position in front of the
upper works 12. As will be explained below, it is desirable to
lower the mast 34 to the fully forward position to permit access to
the upper end of the mast 34 from the ground.
The crane 10 of the preferred embodiment also comprises a pair of
self-raising mast assemblies 64 for raising and lower the mast 34
during the assembling and disassembling of the crane 10. As best
seen in FIGS. 2-6, the self-raising mast assemblies 64 each
comprise a mast raising yoke 66 pivotally supported by a mast
support frame 68 on either side of the upper works 12. The lower
end of each leg 62 of the mast 34 is likewise supported by the mast
support frame 68. These components are preferably arranged so that
the mast 34 and the mast raising yoke 66 have the same axis of
rotation 70 about the upper works 12. However, it should be noted
that it is not necessary for the axis of rotation of the mast
raising yoke 66 to be coincident with the axis of rotation of the
mast 34. As best seen in FIG. 17, each mast support frame 68 of the
preferred embodiment comprises a pair of vertical walls 72 that are
disposed on each side of the leg 62 of the mast 34. The mast
raising yokes 66 are disposed along the inside of the mast support
frame 68 (i.e., to the inside of the legs 62 of the mast 34) (see
FIG. 3). Each leg 62 of the mast 34 is supported by a support pin
74 that extends through the vertical walls 72 of each mast support
frame 68. The mast raising yoke 66 is likewise supported by the
support pin 74.
As best seen in FIG. 6, each mast raising yoke 66 comprises a
forward arm 76 and a rearward arm 78. The forward arm 76 and the
rearward arm 78 each comprise an engagement slot 80, 82 on the
upper surfaces thereof. As will be explained in greater detail
below, the engagement slots 82, 84 are configured so as to engage a
lifting pin 84 on the inside surface of each leg 62 of the mast 34.
In the preferred embodiment, the engagement slot 80 on the forward
arm 76 and the engagement slot 82 on the rearward arm 76 are
separated by an angle of 160.degree. about the axis of rotation 70,
said angle being measured along an arc above the support pin 74. In
other words, if the mast raising yoke 66 is oriented so that the
rearward arm 76 is disposed horizontally (i.e., parallel to the
ground) and towards the rear of the crane 10 (i.e., rearwardly from
the axis of rotation 70), then the forward arm 76 will be disposed
towards the front of the crane 10 (i.e., forwardly from the axis of
rotation 70) and at an angle of 20.degree. above horizontal.
Each self-raising mast assembly 64 further comprises a lever arm 86
that is pivotally connected to the support pin 74 so as to be
pivotal about the axis of rotation 70. The lever arm 86 is welded
or otherwise fastened to the mast raising yoke 66 so that the lever
arm 86 and the mast raising yoke 66 rotate about the axis of
rotation 70 as a unitary component. In other words, the lever arm
86 and the mast raising yoke 66 rotate together. In the preferred
embodiment shown, the lever arm 86 is a sub-component of the mast
raising yoke 66.
Each self-raising mast assembly 64 further comprises a hydraulic
mast raise cylinder 88 that is connected to an end of the lever arm
86. In particular, the upper end of the mast raise cylinder 88
(i.e., the piston rod) is connected to an end of the lever arm 86,
and the lower end of the mast raise cylinder 88 (i.e., the bore) is
connected to the upper works 12. As best seen in FIG. 6, the mast
raise cylinder 88 is arranged so that extension or contraction
thereof will cause the lever arm 86, and in turn the mast raising
yoke 66, to rotate (i.e., pivot) about the axis of rotation 70. As
will be discussed in greater detail below, the mast raise cylinder
88 and the lever arm 86 are preferably configured so that extension
or contraction of the mast raise cylinder 88 will rotate the mast
raising yoke 66 through an angle of approximately 115.degree.. For
example, when the mast raise cylinder 88 is fully contracted, the
rearward arm 76 will be disposed horizontally (i.e., parallel to
the ground) and towards the rear of the crane 10. When the mast
raise cylinder 88 is fully extended, then the rearward arm 76 will
be disposed towards the front of the crane 10 at an angle of
65.degree. above horizontal. The extension and retraction of the
mast raise cylinders 88 is controlled by a hydraulic circuit (to be
described below).
The preferred method of self-assembling the crawler crane 10 is
best seen by referring to FIGS. 7-16 and the description above.
Referring to FIG. 7, the disassembled crawler crane 10 is delivered
to the job site on a transport trailer (not shown). Additional
components, such as the boom top 28, boom inserts 32, and the
counterweights 22 are delivered on separate transport trailers (not
shown) prior to their assembly to the crane 10. Although in the
preferred embodiment shown, the crawlers 24 remain assembled to the
crane 10 during transport between job sites, these components may
be delivered separately and assembled to the crane 10 during the
self-assembly process. A method and apparatus for assembling the
crawlers 24 to the car body 20 are disclosed in U.S. Pat. No.
5,427,256, titled "Crane Upper Works To Lower Works Alignment
System". Another method of assembling the crawlers 24 to the car
body 20 is disclosed in U.S. Pat. No. 5,823,279, titled "Carbody To
Crawler Connection".
As best seen in FIGS. 5 and 7, the mast 34 remains connected to the
upper works 12 during transport of the partially disassemble crane
10 from one job site to another. As explained above, because the
mast 34 is a large and heavy component, it is advantages to keep
the mast 34 assembled to the crane 10. This also avoids the need to
disassemble the boom hoist rigging 38 from between the mast 34 and
the upper works 12. Nevertheless, it is necessary to position the
mast 34 in a collapsed, horizontal position on top of the upper
works 12 for transport. Orienting the mast 34 in this position
allows the overall height and length of the partially disassembled
crane 10 to be reduced so as to avoid most overhead obstacles and
reduce the length of the transport vehicle required. Moreover,
storing the mast 34 onto the rearward portion of the upper works 12
allows the weight of the mast to be more evenly distributed between
the front and rear axles of the transport vehicle (not shown). This
is an important consideration when highway limits on vehicle-axle
loads must be observed.
The preferred method of self-raising the mast 34 is best seen by
referring to FIGS. 6-16 and the description above of the
self-raising mast assemblies 64. As best seen in FIGS. 6 and 7,
when the mast 34 is stored on the rearward portion of the upper
works 12, the lifting pin 84 on the inside of each leg 62 of the
mast 34 is disposed within the rear engagement slot 82 on the
rearward arm 76 of the mast raising yoke 66. Preferably, the
lifting pin 84 is not resting directly on the bottom surface of the
rear engagement slot 82. This prevents the mast 34, which may be
subjected to movement or vibration during transport, from impacting
the mast raising yoke 66.
As best seen in FIG. 6, the rearward arm 76 of the mast raising
yoke 66 is oriented approximately horizontal. This is referred to
as the stored position for the mast raising yoke 66. More
specifically, the center of the rear engagement slot 82 on the
rearward arm 76 is at approximately the same elevation (or slightly
below) as the axis of rotation 70 of the mast 34. For the purpose
of this description of the mast self-raising procedure, the
orientation of mast raising yoke 66 and the mast 34 will be
described in angles measured from a horizontal line extending
rearwardly from the axis of rotation 70. The mast raising yoke 66,
when in the stored position, is therefore defined as being oriented
at 0.degree.. The mast 34, when in the stored position, is likewise
defined as being oriented at 0.degree.. When the mast raising yoke
66 is in the stored position (i.e., at 0.degree.), the mast raise
cylinder 88 is fully retracted. The relative positions of the mast
34, the mast raising yoke 66, and the mast raise cylinder 88, when
in the stored position, are also shown in the schematic of FIG.
11.
Of course, it should be noted that if the axis of rotation of the
mast raising yoke 66 is not coincident with the axis of rotation of
the mast 34, then the relative angles of these components might
differ. For example, if the axis of the mast raising yoke 66 is
below the axis of rotation of the mast 34, then the rearward arm 76
might be oriented at an angle that is above horizontal when the
mast 34 is horizontal.
To initiate the mast self-raising procedure, the mast raise
cylinder 88 is extended so as to apply a force to the end of the
lever arm 86, thereby causing the mast raising yoke 66 to rotate in
a clockwise direction (as viewed in FIG. 6). As the rearward arm 76
of the mast raising yoke 66 swings upward, the rear engagement slot
82 engages the lifting pin 84 on the mast 34. As best seen in FIG.
8, the mast raise cylinder 88 is extended further to continue
rotation of the mast raising yoke 66 so as to pivot the mast 34 up
from the stored position and off of the upper works 12. As the mast
34 is pivoted upwards, the boom hoist rigging 38 must
simultaneously be lengthened to allow the upper end of the mast 34
to freely move away from the rear end of the upper works 12. As
explained above, the boom hoist rigging 38 is lengthened by
rotating the boom hoist drum 46 so as to pay out the boom hoist
rope 40. As will be explained in greater detail below, a slight
tension is maintained in the boom hoist rigging 38 so as to
maintain control of the mast 34. Tension is also maintained in the
boom hoist rigging 38 so as to, for example, maintain proper
spooling of the boom hoist rope 40 on the boom hoist drum 46. It
should be noted that FIG. 8 shows the mast 34 and the mast raising
yoke 66 both at an angle of approximately 45.degree..
As shown in FIG. 9, extension of the mast raise cylinder 88 is
continued until the mast 34 is pivoted past vertical and reaches a
mast angle of approximately 115.degree.. At a mast angle of
115.degree., the weight and the location of the center of gravity
of the mast 34 are sufficient to maintain the mast 34 in a forward
leaning orientation. In other words, the boom hoist rigging 38 can
safely support the mast 34 once the mast 34 has reached a mast
angle of 115.degree.. Although this angle is considered to be the
upper end of the safe operating range for the mast 34 while using
only the boom hoist rigging 38, it should be appreciated that the
mast 34 may be used above this range by utilizing the boom hoist
rigging 38 in conjunction with the mast raising yoke 66. In other
words, and as will be explained below, the mast 34 can be operated
at angles between 90.degree. and 115.degree. by using the boom
hoist rigging 38 together with the mast raising yoke 66. The
relative positions of the mast 34, the mast raising yoke 66, and
the mast raise cylinder 88, in this position, are also shown in the
schematic of FIG. 12.
Of course, it should be noted that as the mast 34 approaches
vertical, it can become unstable, and may move unpredictably in
response to wind loads or vibrations from crane machinery. Thus, it
is very important that tension be maintained in the boom hoist
rigging 38 as the mast 34 approaches vertical. In other words, as
the mast raising yoke 66 is applying a force to the mast 34 in one
direction (i.e., pushing the mast 34 towards the front of the crane
10), the boom hoist rigging 38 must simultaneously apply a force to
the mast 34 in the opposite direction (i.e., pulling the mast 34
towards the rear of the crane 10). These two opposing forces
stabilize the mast 34.
Likewise, when the mast 34 moves (i.e., pivoted) past vertical,
forward pressure is maintained on the mast 34 by the mast raising
yoke 66. This forward pressure keeps the mast 34 from being tipped
backwards by the weight of the boom hoist rigging 38 or any wind
loads that may act on the mast 34. As explained above, once the
mast has reached a mast angle of 115.degree., the weight and the
location of the center of gravity of the mast 34 are sufficient to
maintain the mast 34 in a forward leaning orientation, and it is no
longer necessary for the mast raising yoke 66 to apply pressure to
the mast 34.
Beyond a mast angle of 115.degree., the mast 34 is lowered towards
the front of the crane 10 by continuing to extend the boom hoist
rigging 38. At this time, the mast raise cylinder 88 is retracted
so as to rotate the mast raising yoke 66 back to the stored
position (i.e., 0.degree.). As the mast raising yoke 66 is rotated
back to the stored position (in a counter-clockwise direction as
viewed in FIG. 9), the rear engagement slot 82 disengages and moves
away from the lifting pin 84 on the leg 62 of the mast 34. In other
words, the mast 34 is no longer supported by the mast raising yoke
66 once the mast 34 moves beyond 115.degree..
As shown in FIG. 10, the mast 34 is further lowered by extending
the boom hoist rigging 38 until the mast 34 reaches a mast angle of
approximately 160.degree. (i.e., 20.degree. above horizontal as
measured from the front of the crane 10). Beyond this angle, boom
hoist rigging 38 can no longer safely support the mast 34. This is
because the direction of the force being applied to the mast 34 by
the boom hoist rigging 38 is nearly parallel with the mast 34, and
therefore does not apply a sufficient force perpendicular to the
mast 34 to keep the mast 34 from continued rotation about the axis
of rotation 70. Moreover, the forces applied to the mast 34 by the
boom hoist rigging 38 at these angles may cause the mast 34 to
buckle.
Although 160.degree. is considered to be the lower end of the safe
operating range for the mast 34 while using only the boom hoist
rigging 38, it should be appreciated that the mast 34 may be used
below this range by utilizing the mast raising yoke 66, either
alone or in conjunction with the boom hoist rigging 38. In other
words, the mast 34 can be operated at angles between 160.degree.
and 180.degree. by using the mast raising yoke 66.
As the mast approaches a mast angle of 160.degree., the mast raise
cylinder 88 is retracted so as to rotate the mast raising yoke 66
to the stored position (i.e., 0.degree.). As explained above, when
the mast raising yoke 66 of the preferred embodiment is in the
stored position (see FIG. 6), the forward arm 76 of the mast
raising yoke 66 is disposed approximately 20.degree. above
horizontal. In this position, the front engagement slot 80 on the
forward arm 76 engages the lifting pin 84 on the leg 62 of the mast
34 when the mast 34 is at a mast angle of 160.degree. (i.e., is
20.degree. above horizontal). In other words, the mast raising yoke
66 is positioned so as to support the mast 34 when the mast 34
reaches the lower end of the range wherein it can be supported by
the boom hoist rigging 38 alone. The relative positions of the mast
34, the mast raising yoke 66, and the mast raise cylinder 88, in
this position, are also shown in the schematic of FIG. 13. Of
course, these angles may be different if the center of rotation of
the mast raising yoke 66 is not coincident with the center of
rotation of the mast 34.
To lower the mast 34 further (i.e., beyond a mast angle of
160.degree.), the mast raise cylinder 88 is extended to rotate the
mast raising yoke 66 (in a clockwise direction as viewed in FIG.
10) and thereby lower the forward arm 76. Because the boom hoist
rigging 38 is nearly parallel with the mast 34, the weight of the
mast 34 is fully supported by the mast raising yoke 66. However,
the boom hoist rigging 38 must still be extended to permit the mast
34 to be lowered by the mast raising yoke 66.
In the preferred method of self-assembling the crane 10, the mast
34 is lowered to a mast angle of approximately 177.degree. (see the
schematic of FIG. 14) by extending the mast raise cylinder 88. At
this angle, the end of the mast 34 is low enough to the ground to
allow the rigging of a load hoist line 50 through the sheave
assembly 42 on the end of the mast 34. Once a load hoist line 50
has been rigged, the mast 34 is then raised back up to a mast angle
of 160.degree. (i.e., more than 20.degree. above horizontal) (see
FIG. 10) by contracting the mast raise cylinder 88. Once the mast
34 has been raised above a mast angle of 160.degree., then the boom
hoist rigging 38 alone can be used to control the angle of the mast
34.
With the load hoist line 50 rigged to the mast 34, the mast 34 can
be used to lift and position additional crane components to the
crane 10. For example, the crawlers 24, if not previously assembled
to the crane 10, can be lifted, positioned and assembled to the
crane. Likewise, the counterweights 22 can be assembled to the
crane 10 at this time. As shown sequentially in FIGS. 15 and 16,
the mast 34 can also be used to assemble the boom butt 30, the boom
inserts 32 and the boom top 28 to the upper works 12 of the crane
10.
While using the mast 34 to assemble additional crane components,
the mast raise cylinder 88 is preferably fully extended so as to
place the mast raising yoke 66 at an angle of 115.degree.. When
oriented at this angle, the mast raising yoke 66 serves as a
backstop for the mast 34 to prevent the mast 34 from accidentally
rotating back past vertical and collapsing onto the back of the
upper works 12. This is particularly important when assembling
components close to the crane 10, such as the crawlers 24, because
the mast 34 must be positioned very close to vertical (i.e., a mast
angle of 90.degree.). As previously explained, the mast 34 can be
very unstable when in a nearly vertical position. In addition, when
the mast 34 is between 115.degree. and 90.degree., the mast 34 must
be controlled by using the mast raising yoke 66 in conjunction with
the boom hoist rigging 38.
Once the boom 26 and other crane components have been assembled to
the crane 10, the mast 34 is lowered down towards the front of the
crane 10 and on top of the boom 26 for final rigging. Using the
same procedure as described above, the mast raise cylinder 88 and
the mast raising yoke 66 are used to lower the mast 34 when the
mast angle is greater than 160.degree. (i.e., less than 20.degree.
above horizontal). With the mast 34 resting on top of the boom 26,
the load hoist line 50 can be reeved about the sheaves 54 at the
end of the boom top 28, and the boom pendants 36 can be likewise
connected thereto.
Once finally rigging of the boom 26 is complete, then the mast
raise cylinder 88 and the mast raising yoke 66 are used to raise
the mast 34 above a mast angle of 160.degree. (i.e., more than
20.degree. above horizontal). Above this mast angle, the mast 34 is
raised and controlled by the boom hoist rigging 38 so as to raise
the boom 26 off of the ground and place the crane 10 into
operational mode (as shown in FIG. 1). At this time, the mast raise
cylinder 88 is contracted so as to return the mast raising yoke 66
to the stored position. This prevents mast raising yoke 66 from
interfering with the movement of the mast 34 during normal crane
operations.
Self-disassembly of the crane 10 is accomplished by following the
method described above in reverse order.
Although the mast 34 was described above as having an operational
range of between 90.degree. and 180.degree. (between 115.degree.
and 160.degree. when using the boom hoist rigging 38 alone), it
should be noted that this range was only applicable when using the
mast 34 during crane self-assembly and self-disassembly (e.g., when
using the mast 34 to lift and assemble crane components to the
crane 10). As can be seen in FIG. 1, the mast 34 has a different
range of motion when connected to the boom 26. This is because the
boom 26 applies a significant force to the end of the mast 34 that
is opposite to the force that is applied to the mast 34 by the boom
hoist rigging 38. Thus, the mast 34 is stable as long as the boom
26 is within the normal boom operating range.
Likewise, it should be apparent that the various angles discussed
above are dependent on the geometry of the crane 10 and the
components thereof. Thus, cranes having different geometries or
different components may require a mast raising cylinder having a
different configuration, or a mast cylinder with a different stroke
length. Such changes or modifications should be within the skill of
those skilled in the art of cranes and related machinery.
Although the above-described method and the specific operations
therein can be manually controlled and coordinated by the crane
operator, some of these operations are preferably performed or
assisted by a microprocessor-based controller (i.e., computer) (not
shown) on the crane 10. In particular, it can be very difficult to
control both the mast raise cylinder 88 and the boom hoist rigging
38 during the mast self-raising procedure. For example, and as
described above, when raising the mast 34 from the stored position,
the operator must manipulate a first control to extend the mast
raise cylinder 88 and rotate the mast raising yoke 66. The operator
must simultaneously manipulate a second control to extend the boom
hoist rigging 38. If the boom hoist rigging 38 is extended too
quickly relative to the rotation of the mast raising yoke 66 (and
the motion of the mast 34), then too much slack may be created in
the boom hoist rope 40, which may then tangle with other crane
components or become fouled in the sheave assemblies 42, 44, or
which may allow the boom hoist rope 40 to unspool from the boom
hoist drum 46. On the other hand, if the boom hoist rigging 38 is
extended to slowly relative to the rotation of the mast raising
yoke 66, then the mast 34 may collapse in response to loads applied
thereto by the boom hoist rigging 38 and the mast raising yoke 66.
Moreover, and as explained above, precise control of the boom hoist
rigging 38 and the mast cylinder is particularly important when the
mast 34 is near vertical or in the fully forward position (and very
unstable).
In addition to the above, the operator may forget to perform
certain steps in the mast self-raising procedure. For example, the
operator may forget to place the mast raising yoke 66 into the
stored position before lowering the mast 34 past the lower end of
the operating range (i.e., below a mast angle of 160.degree.). If
so, then the mast 34 may become unstable and fall to the ground as
it nears horizontal. The operator may also forget to place the mast
raising yoke 66 into the mast backstop position (i.e., 115.degree.)
while using the mast 34 for crane assembly. Thus, it is preferable
that at least some of the operations performed during the mast
self-raising procedure be performed or assisted by a
microprocessor-based controller or computer.
As shown schematically in FIG. 18, the mast raise cylinders 88 of
the self-raising mast assemblies 64 utilize a closed loop hydraulic
system. This closed loop system is, however, hydraulically
connected to the load hoist pump 90 (i.e., the hydraulic pump used
to rotate the load hoist drum), which supplies hydraulic pressure
thereto. The microprocessor-based controller is connected to the
load hoist pump 90, the boom hoist pump 92, load pins 94 attached
to each of the mast raise cylinders 88, the control valve 96 and
the pressure transducer 98. The controller can receive electrical
signals from each of the load pins 94, the pressure transducer 98,
the mast angle indicator 100 and the operator's control handle 102.
The electrical signals from the load pins 94 are proportional to
the mast loading on each mast raise cylinder 88. The electrical
signal from the pressure transducer 98 is proportional to the
hydraulic pressure generated by the load hoist pump 90. The
electrical signals from the mast angle indicator 100 and the
control handle 102 are proportional to mast angle and handle
position, respectively. The controller can source electrical
signals that control the flow output of the load hoist pump 90 and
the position of the control valve 102.Software that is resident in
the controller runs a routine that semi-automates the mast raising
and lowering operation via the boom hoist pump 92, the load hoist
pump 90 and the control valve 96. The mast raising and lowering is
commanded from the operator's control handle 102. During the
raising or lowering sequence the boom hoist rope 40 and the mast
raise cylinders 88 must simultaneously (or alternately) restrain
the mast 34 from falling and/or lift it into position.
In the preferred method of self-raising the mast 34, the crane
operator uses the computer to place the crane 10 into set-up mode
the crane operator then initiates the mast self-raising procedure
by depressing the operator control handle 102. In response thereto,
the computer will then begin to simultaneously pay out the boom
hoist rope 40 and extend the mast raise cylinders 88 so as to raise
the mast 34.
In the preferred method, the computer maintains a slight tension in
the boom hoist rigging 38, which helps to maintain control of the
mast 34 during the self-raising procedure. Utilizing the electrical
signals from the two load pins 94, the mast angle indicator 100 and
the pressure transducer 98, flow from the load hoist pump 90 and
the boom hoist pump 92 are controlled during the raise/lower
operations to maintain the proper restraining and lifting load
combinations between the boom hoist rope 40 and the mast raise
cylinders 88.
Electrical signals from the mast angle indicator 100 and the
operator's control handle 102 are used to position the mast raise
cylinders 88, and in turn the mast raising yoke 66, in the proper
orientation so as to receive the mast 34 as it is lowered towards
the full-forward position (i.e., beyond a mast angle of
160.degree.), or as it is raised back towards vertical. In other
words, if the crane 10 is in "set-up" mode, then the computer will
monitor the angle of the mast 34 and coordinate the boom hoist
rigging 38 and the self-raising mast assemblies 64 so as to safely
maintain control of the mast 34 at all times during the mast
self-raising procedure.
Additional sensors, such as pressure and speed sensors, may also be
used to monitor the boom hoist rope tension and speed to provide
additional monitoring mechanisms to ensure safe mast 34
self-raising and operating procedures.
It should be appreciated that the apparatus and methods of the
present invention are capable of being incorporated in the form of
a variety of embodiments, only a few of which have been illustrated
and described above. The invention may be embodied in other forms
without departing from its spirit or essential characteristics. The
described embodiments are to be considered in all respects only as
illustrative and not restrictive, and the scope of the invention
is, therefore, indicated by the appended claims rather than by the
foregoing description. All changes which come within the meaning
and range of equivalency of the claims are to be embraced within
their scope.
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